I dont know if this will work but this is how I clean coral for aquariums. Remove as much soft tissue as possible, Then soak the scull in a solution of Bleach and water. Make it pretty strong. Let it soak for about a week. Keep refreshing the bleach. periodically remove more tissue.
Dont know if it will work. If you try it let me know if it worked for a skull.
I have cleaned a skull but in a strange way. I set it out in the shade during the summer on a bunch of wire. I left it out most of the summer, the wire keep animals from getting it. At the end of the summer it was clean and bleached.
If you could find some, get carrion beattles and put a few on it in a closed container and let them do their work.
dont know if I helped at all, guess I just needed to type.<img src=icon_smile_big.gif border=0 align=middle>
"Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity" Martin Luther King Jr.